So, I got this brilliant idea that I would do a simple experiment demonstrate the three states of matter. When I was in high school, our chemistry program used the same experiment to demonstrate everything--fill a balloon with baking soda, fill a 2 liter bottle with vinegar, and then do different things with the same experiment. Our class was enlivened by the fact that the mom in charge of lab always brought water balloons--the trying process of trying to ram 20 grams of baking soda into a tinny balloons stands out in my memory right up there with the fact that as we gingerly held the tinny balloons on the bottles, they would inflate to their full capacity and burst by your face dusting you group with a fine powder of baking soda. Good times!
So, I remembered that experiment, and decided that if I tinted the vinegar blue for visibility, it would be a great experiment to do for my kids. So, I duly dumped a good bit of vinegar into a 2 liter bottle, filled a LARGE balloon with a a generous amount of baking soda, and put in the food coloring. I vaguely remembered that the experiment was always rather pathetic, and I wanted that balloon to inflate, so I put in a good amount of both components.
The next day I duly placed my loaded bottle in a plastic tray I had just brought up for the kids to put their health assignments in, gave my little talk about the three states of matter, put the balloon on the bottle neck, tipped it up, and let 'er go. Well, all went well for the first bit--the reaction started, the balloon started to inflate, all was well and good. Then, I noticed the hole in the balloon that was letting vinegar smelling gas out. Then, I noticed that I had started something a little bigger than my bottle could contain! As I watched in horror, blue vinegar started to spurt merrily out the hole in the balloon and all over one of my 5th graders notes. I grabbed the spurting balloon and directed the spray down, but not before the notebook was liberally splattered, and a howl of shock and appreciation was let loose by my riveted class. Once the reaction was finished, I sent a kid for a rag to wipe up the floor and desks that had been spattered, and tried to recover with something approaching grace. Ah, life is never boring! I'll go down in history as the teacher who sprayed the class blue!